Sonar transducer assembly having a printed circuit board with flexible element tabs

ABSTRACT

An example sonar transducer assembly is provided including at least one transducer element and a flexible printed circuit board (PCB) including at least one set of electrical connections for the at least one transducer element. The electrical connections include flex tabs configured to flex out of a PCB plane. The sonar transducer assembly also includes a support structure including an aperture for the at least one transducer element. The support structure is configured to support the body of the PCB, allow flexion of the flex tabs into the aperture, and retain the at least one transducer element in the at least one aperture. The transducer element is installed in a direction that is perpendicular to the PCB plane causing the flex tabs to flex outwardly from the PCB plane, thereby creating an elastic force of the flex tabs applied against opposing ends of the at least one transducer element.

FIELD OF THE INVENTION

Embodiments of the present invention relate generally to sonartransducer assemblies, and more particularly, to sonar transducerassemblies having a printed circuit board with flexible element tabsconfigured to hold transducer elements.

BACKGROUND OF THE INVENTION

Sonar (SOund Navigation And Ranging) is used to detect waterborne orunderwater objects. For example, sonar devices may be used to determinedepth and bottom topography, detect fish, locate wreckage, etc. Sonartransducer elements, or simply transducers, convert electrical energyinto sound or vibrations at a particular frequency. A sonar sound beamis transmitted into and through the water and is reflected from objectsit encounters. The transducer receives the reflected sound (the “sonarreturns”) and converts the sound energy into electrical energy. Based onthe known speed of sound, it is possible to determine the distance toand/or location of the waterborne or underwater objects. The sonarreturn signals can also be processed to be displayed on a displaydevice, giving the user a “picture” of the underwater environment.

Applicant herein provides improved techniques and assemblies forproducing sonar transducer assemblies.

BRIEF SUMMARY OF THE INVENTION

Sonar transducer assemblies may be formed, in some cases, using one ormore transducer elements that are installed or mounted in mechanical andelectrical contact with a printed circuit board (PCB). The transducerelements may be soldered to the electrical contact pads on the PCB. ThePCB is an elastic wave bearing structure. Acoustic transducer elements,such as used in sonar systems, attached to the PCB are, in general,points of coupling incoming sound from the environment into the variouselastic wave types supported by the PCB. The elastic waves, so excited,may propagate in all directions within the PCB, scattering from thevarious boundaries and attached structures (e.g. discrete electricalcomponents), leading to a frequency- and location-dependent feedback tothe transducer elements. The electrical output of the transducerelements can be, therefore, a combination of direct acoustic stimulationby the incoming sound plus indirect stimulation due to feedback throughthe elastic structure of the PCB. For brevity, the term “elasticresponse” shall be used to refer to the unwanted feedback from thestructure to which the transducer elements are attached.

When, for the purpose of producing an array of spatially-arrangedreceivers or transmitters, more than one transducer element is placed ina sonar system, it is desirable, in order to effectively apply simplebeamforming algorithms, that the electrical signals transduced by thetransducer elements be uniform simple functions of the acoustic fieldthat they are intended to sample (in the case of receiving) or produce(in the case of transmitting). Physical connections between thetransducer elements and the PCB may not only produce an undesired signalinvolving the PCB as an elastic wave-bearing medium, but the mechanicalimpedance of the connections may also have a local effect on thefrequency response of the transducer elements, e.g. mass loading bysolder at the attachment points of the transducer elements.Inconsistencies in the mechanical boundary conditions at the point ofelectrical connections in addition to the elastic response of the PCBmay cause undesired, chaotic electrical signals to be produced by thetransducer elements, which may, for example, degrade the sonar image.

Some embodiments of the present invention contemplate a flex tabarrangement for the PCB of a sonar transducer assembly. Such a flex tabarrangement may mitigate the undesired signals caused by the elasticresponse of the PCB. Additionally, the element-to-element variationsacross the transducer assembly caused by inconsistencies in themechanical boundary conditions due to inconsistent solder joints may bemitigated by removing the solder connection altogether.

In some embodiments, the PCB may include a set of flexible electricalconnection tabs for each transducer element, e.g. piezoelectric crystal.The transducer element may be inserted into a section of the PCB betweenthe flex tabs, thereby causing the flex tabs to flex outwardly from aplane defined by the PCB. In some embodiments, the flexion of the flextabs outwardly of the PCB plane may cause an elastic force on each ofthe flex tabs to be applied to opposing ends of the transducer elementsto create an electrical connection. In some embodiments, the flexion ofthe flex tabs may mechanically isolate the ends of the transducerelements from the PCB, thereby mitigating or eradicating interferencefrom the elastic response of the PCB.

In this regard, in some embodiments, the transducer elements may not beaffixed, such as by solder or adhesive, to the PCB. Instead, the forceapplied by the flex tabs on opposing ends of the installed transducerelement may be sufficient to maintain the position of the transducerelement as well as maintain an electrical connection to the transducerelement. The removal of the solder connection to the PCB may furthereliminate transference of the resonance waves from the transducerelements to the PCB. Further, removal of the solder connection may alsoremove inconsistences in the mechanical boundary conditions of theelectrical connections to the transducer elements, thereby reducingelement-to-element variations across the transducer assembly and, insome cases, increasing the sharpness of the sonar image.

In an example embodiment, a sonar transducer assembly is providedincluding at least one transducer element and a flexible printed circuitboard (PCB) including at least one set of electrical connections for theat least one transducer element. The electrical connections include flextabs configured to flex out of a PCB plane defined by a body of the PCB.The sonar transducer assembly also includes a support structureincluding at least one aperture for the at least one transducer element.The support structure is configured to support the body of the PCB,allow flexion of the flex tabs into the aperture, and retain the atleast one transducer element in the at least one aperture. Thetransducer element is installed into the aperture in a direction that isperpendicular to the PCB plane causing the flex tabs to flex outwardlyfrom the PCB plane and the flexion of the flex tabs causes an elasticforce of the flex tabs to be applied against opposing ends of the atleast one transducer element.

In another example embodiment, a sonar transducer assembly is providedincluding a plurality of transducer elements, and a flexible printedcircuit board (PCB) including a plurality of sets of electricalconnections for the plurality of transducer elements. Each of theplurality of sets of electrical connections comprise flex tabsconfigured to flex out of a PCB plane defined by a body of the PCB. Thesonar transducer assembly also includes a support structure including aplurality of apertures. Each of the plurality of apertures is configuredto receive each of the plurality of transducer elements and the supportstructure is configured to support the body of the PCB, allow flexion ofeach of the flex tabs into a respective aperture of the plurality ofapertures, and retain each of the plurality of transducer elements inthe respective aperture of the plurality of apertures. Each of theplurality of transducer elements is held in the PCB and the supportstructure through an interference fit, wherein each of the plurality oftransducer elements is installed between the flex tabs.

In still a further example embodiment, a sonar transducer assembly isprovided including at least one transducer element and a flexibleprinted circuit board (PCB) including at least one set of electricalconnections for the at least one transducer element. The electricalconnections include flex tabs configured to flex out of a PCB planedefined by a body of the PCB, the at least one transducer element isinstalled between the flex tabs, and flexion of the flex tabs causes anelastic force of the flex tabs to be applied against opposing ends ofthe at least one transducer element.

In an example embodiment, the at least one transducer element is notaffixed to the PCB.

In some example embodiments, the at least one set of electricalconnections also includes point contacts extending outwardly from theflex tabs toward the at least one transducer element to increasepressure applied by the flex tabs on the at least one transducerelement. In an example embodiment, the point contacts each include adimple in a contact pad or an electrically conductive material added toa contact pad.

In some example embodiments, the at least one transducer elementincludes a plurality of transducer elements and the at least oneaperture includes a plurality of apertures. Each of the plurality oftransducer elements is disposed in a separate one of the plurality ofapertures and the support structure and PCB provide resonance isolationfor each of the plurality of transducer elements.

In an example embodiment, the support structure includes foam. In someexample embodiments, the foam provides resistance to the flexion of theflex tabs to cause an increase in the elastic force applied to theopposing ends of the at least one transducer element. In an exampleembodiment, the aperture includes an H cut configured to enable a foamtab to flex out of a foam plane defined by a foam body.

In some example embodiments, the support structure also includes a basefoam disposed on a first side of the foam and a top foam disposed on asecond side of the foam. In an example embodiment, the top foam includesa slot cut configured to receive expanding foam therethrough. In someexample embodiments, the base foam includes an element aperture for theat least one transducer element and the element aperture is configuredto receive at least a portion of the flex tabs or a portion of the foamwhen the flex tabs are flexed.

In an example embodiment, the support structure includes a chassisformed from a rigid structural material.

In some example embodiments, at least a portion of the transducerassembly is filled with an expanding foam that is configured to retainthe relative position of the at least one transducer element withrespect to the support structure and the PCB.

In an example embodiment, the sonar transducer assembly also includes ahousing configured to enclose the at least one transducer element, thesupport structure, and the PCB within a watertight volume and at least aportion of the housing that encloses the at least one transducerelement, the support structure, and the PCB is filled with a pottingmaterial.

In some example embodiments, at least one of the PCB or the supportstructure includes a plurality of guide holes or notches configured tobe positioned about a guide post or rib of an assembly fixture duringassembly to align the PCB with the support structure.

Some example embodiments of the present invention include example sonartransducer assemblies and methods of manufacture thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

Having thus described the invention in general terms, reference will nowbe made to the accompanying drawings, which are not necessarily drawn toscale, and wherein:

FIG. 1 illustrates an example transducer array;

FIG. 2A illustrates an example printed circuit board in accordance withsome embodiments discussed herein;

FIGS. 2B and 2C illustrate an example transducer element and an examplecorresponding set of flex tabs of a printed circuit boards in accordancewith some embodiments discussed herein;

FIG. 3 illustrates another example printed circuit board in accordancewith some embodiments discussed herein;

FIGS. 4A-4C illustrate example installation of a transducer element intoa printed circuit board with flex tabs in accordance with some exampleembodiments discussed herein;

FIG. 5 illustrates a perspective view of an example transducer assemblyin accordance with some example embodiments discussed herein;

FIG. 6 illustrates a cross sectional view of the example transducerassembly shown in FIG. 5, in accordance with some example embodimentsdiscussed herein;

FIG. 7 illustrates an exploded view of a portion of an exampletransducer assembly in accordance with some example embodimentsdiscussed herein;

FIGS. 8 and 9 illustrate exploded views of an example transducerassembly in accordance with some example embodiments discussed herein;

FIG. 10 illustrates an example transducer assembly positioned within atransducer assembly housing in accordance with some example embodimentsdiscussed herein;

FIGS. 11A and 11B illustrate a flow chart of an example method ofassembling an example transducer assembly in accordance with someexample embodiments discussed herein;

FIGS. 12A and 12B illustrate example base foams and middle foamsincluding apertures in accordance with some example embodimentsdiscussed herein;

FIGS. 13A and 13B illustrate example installations of a base foam on anassembly fixture in accordance with some example embodiments discussedherein;

FIG. 14A illustrates an example installation of a base foam, a middlefoam, and a PCB on an assembly fixture in accordance with some exampleembodiments discussed herein;

FIGS. 14B and 14C illustrate example installations of a base foam, amiddle foam, a crystal chassis, and PCB on an assembly fixture inaccordance with some example embodiments discussed herein;

FIGS. 15A and 15B illustrate example top foams including apertures inaccordance with some example embodiments discussed herein;

FIGS. 16A and 16B illustrate example installations of top foam on anassembly fixture in accordance with some example embodiments discussedherein;

FIG. 17 illustrates example insertion and alignment of a flex tail ofthe PCB with a chassis front in accordance with some example embodimentsdiscussed herein;

FIG. 18 illustrates example installation of the chassis front on anassembly fixture in accordance with some example embodiments discussedherein;

FIG. 19 illustrates example transducer elements on an adhesive strip inaccordance with some example embodiments discussed herein;

FIGS. 20A and 20B illustrate an example installation of a transducerelement into an aperture in accordance with some example embodimentsdiscussed herein;

FIGS. 21A and 21B illustrate an example transducer assembly with thetransducer elements installed in accordance with some exampleembodiments discussed herein;

FIG. 22 illustrates example installation of guard material about anaperture in a top foam in accordance with some example embodimentsdiscussed herein;

FIG. 23 illustrates an example pouring of expansion foam into anaperture in a top foam in accordance with some example embodimentsdiscussed herein;

FIG. 24 illustrates an example full expansion of the expansion foam inaccordance with some example embodiments discussed herein;

FIG. 25 illustrates an example transducer assembly removed from anassembly fixture in accordance with some example embodiments discussedherein;

FIG. 26 illustrates an example transducer assembly with a release filmremoved in accordance with some example embodiments discussed herein;

FIG. 27 illustrates an example flex tail positioner installed on atransducer assembly in accordance with some example embodimentsdiscussed herein;

FIG. 28 illustrates an example transducer assembly positioned at apredetermined tilt angle in accordance with some example embodimentsdiscussed herein;

FIG. 29 illustrates an example potting material being poured over atransducer assembly in accordance with some example embodimentsdiscussed herein;

FIG. 30 illustrates an example transducer assembly including pottingmaterial in accordance with some example embodiments discussed herein;and

FIG. 31 illustrates an example emitting face of an assembled transducerassembly in accordance with some example embodiments discussed herein.

DETAILED DESCRIPTION

Exemplary embodiments of the present invention now will be describedmore fully hereinafter with reference to the accompanying drawings, inwhich some, but not all embodiments of the invention are shown. Indeed,the invention may be embodied in many different forms and should not beconstrued as limited to the exemplary embodiments set forth herein;rather, these embodiments are provided so that this disclosure willsatisfy applicable legal requirements. Like reference numerals refer tolike elements throughout.

FIG. 1 illustrates an example transducer assembly 100. The transducerassembly 100 may include a printed circuit board (PCB) 102 and aplurality of transducer elements 104 arranged in an array. Each of thetransducer elements 104 may be a piezoelectric crystal that is surfacemounted to the PCB 102. In some embodiments, each of the transducerelements 104 may be directly affixed to the PCB 102, such as by a solderjoint 106. The transducer elements 104 may each have one or moreconductive surfaces, such as at each end of the transducer element. Theconductive surface of the transducer element may be soldered to aconductive pad disposed on the surface of the PCB 102.

In some cases, the solder joints 106 may cause non-uniformity of themechanical boundary conditions at the electrical contacts for eachtransducer element 104 of the transducer array 100. For example, thenon-uniformity may be caused by the adhesion of the solder to thetransducer element 104 and/or the conductive surface on the PCB 102,variations in the amount of solder material in the solder joint 106,variations in the distribution of the solder material in the solderjoint 106, impurities in the solder joint 106, or the like. In somecases, affixing the transducer elements 104 to a face of the PCB 102 mayenable translation, or transfer, of resonate vibrations of thetransducer elements 104 to the PCB 102 causing an elastic response, e.g.resonance waves 108. For example, formed resonance waves 108 maypropagate across a substrate of the PCB 102 and reflect off one or moreedges, or boundaries, of the substrate, thereby causing further elasticresponse, e.g. reflection waves. The resonance waves 108 and associatedreflections may cause vibrations in the transducer elements 104, whichmay ultimately form undesirable signals, e.g. interference, in the sonarsignals.

In some cases, the PCB 102 may include a first layer PCB and a secondlayer PCB. The first layer of the PCB 102 may be disposed on a firstside of the transducer element and the second layer of the PCB may bedisposed on the second side of the transducer element. Each of the firstlayer and second layer of the PCB 102 may include a conductive pad, suchthat the transducer element 104 is connected at a first end to theconductive pad of the first layer of the PCB 102 and connected at asecond end to a conductive pad of the second layer of the PCB 102. Insuch a manner, the transducer element(s) may be “sandwiched” between thefirst layer and second layer of the PCB 102. Such a two layer assemblymay result in some reduction of the translation of the elastic response,e.g. resonate vibrations of the transducer elements 104. However, thesolder joints 106 or other methods of affixing of the transducerelements 104 to the PCB 102 may also have significant translation ofresonate vibrations therebetween.

Some embodiments of the present invention contemplate various transducerassemblies that reduce the variations in mechanical boundary conditionswithin the transducer assembly, such as may be formed based on themechanical connections between the transducer elements and a PCB,thereby reducing element-to-element variations across the transducerassembly and, in some cases, increasing the sharpness of the sonarimage. In some embodiments, example transducer assemblies describedherein may also reduce translation of the resonate vibration of thetransducer elements to the substrate of the PCB, thereby mitigating oreradicating interference from the elastic response of the PCB.

FIGS. 2A and 3 each illustrate an example printed circuit board (PCB)200 in accordance with some embodiments discussed herein. The PCB 200may include a flexible substrate 201, such as a Mylar film or othersuitable material, and two or more conductive traces 204, such as coppertraces or other suitable conductive material. The flexible substrate 201may encapsulate the conductive traces 204, with the exception of contactpads 205 as discussed below, providing electrical insulation to theconductive traces 204. The body of the PCB 200 may be defined as theportion of the PCB 200 including electrical connections and circuitcomponents other than the off board circuit traces.

The conductive traces 204 may be connected at one end to a flexibleelement tab, e.g. flex tab 202. In some embodiments, a contact pad 205may be formed on the flex tab 202 and configured to interact with an endof the transducer element (such as described herein). In some suchembodiments, the conductive traces 204 may be connected to the contactpads 205, such as to ultimately be electrically connected to aninstalled transducer element. In some embodiments, the contact pads 205may be electrically conductive. Additionally or alternatively,conductive traces 204 may pass through the contact pads 205 so as to beelectrically connected to an installed transducer element.

The flex tabs 202 may be attached at one or more ends (e.g., end 294) toa body 201 of the PCB 200 that defines a PCB plane. Additionally, one ormore other ends or sides (e.g., sides 291, 292 and end 293) may beunattached to a body of the PCB 200 for at least a portion of theperiphery of the flex tab 202 thereby enabling flex tabs 202 to flex,e.g. bend, outwardly from a PCB plane defined by the body of the PCB200. In some embodiments, one end 293 and sides 291, 292 of the flextabs 202 may be dye cut, laser cut, or otherwise detached from the bodyof the PCB 200. The flexible substrate a 201 and conductive traces 204may bend or flex at the junction of the attached side 294 of the flextab 202 and the body of the PCB 200.

The conductive pads 205 of the flex tabs 202 may be formed of anysuitable conductive material of high conductance, such as gold, silver,copper, non-metallic conductors, or the like. The conductive pads 205may be formed of the same material as the conductive traces 204, such asby acid etching or other suitable method. The conductive pads 205 may bean extension of the conductive traces 204 that are not covered by theflexible substrate 201, such that the conductive pads 205 may be indirect contact with an end of a transducer element 302, such asillustrated conceptually in FIG. 2B.

In an example embodiment, with reference to FIG. 2B, the flex tabs 202may be disposed as a flex tab pair including a first flex tab 202A and asecond flex tab 202B. The flex tab pair 202A, 202B may have attachedends 294 disposed at a far end from the unattached end 293, such thatwhen the flex tabs 202 flex out of the PCB plane. In some embodiments,the flex tab pair 202A, 202B are configured to flex away from eachother. The transducer element 302 may be inserted, or installed into anopening 299 created by flexion of the flex tabs 202A, 202B outwardlyfrom the PCB plane. The transducer element 302 may include a firstconductive element (e.g., portion) 350A disposed at a first end of thetransducer element 302 and a second conductive element (e.g., portion)350B disposed at a second end of the transducer element 302 (in someembodiments, the entire or different portions of the transducer elementmay be conductive). When installed into the PCB 200 (such as illustratedin FIGS. 4A-4C) flexion of the flex tab pair 202A, 202B causes the firstflex tab 202A to generate a reactionary elastic force in the directionof the second flex tab 202B and the second flex tab 202B to generate areactionary elastic force in the direction of the first flex tab 202A.The elastic force may cause the first conductive pad 205A of the firstflex tab 202A to contact the first conductive element 350A of thetransducer element 302 and the second conductive pad 205B of the secondflex tab 202B to contact the second conductive element 350B of thetransducer element 302. The contact between the first conductive pad205A with the first conductive element 350A and the second conductivepad 205B with the second conductive element 350B may create anelectrical path across the flex tab pair 202A, 202B and the transducerelement 302.

In some embodiments, one or more of the contact pads 205 on the flextabs 202 may include a point contact 207. For example, with reference toFIG. 2C, a first point contact 207A is disposed on the first flex tab202A and a second point contact 207B is disposed on the second flex tab202B. The point contacts may each extend outwardly away from thecorresponding flex tab 202 toward the transducer element 302, wheninstalled in the PCB 200, such as depicted in FIGS. 2A and 2C. In anexample embodiment, the point contacts may be a set of dimples. Thedimples may be formed on the contact pad 205 by warping the substrate201 and contact pad 205, such as by applying force to a dye in contactwith the contact pad 205. Alternatively, the point contacts 207 may beformed by adding a predetermined amount of conductive material, e.g.solder, to a portion of the conductive pad 205. In some embodiments, thepredetermined amount of conductive material may have a precise mass loadfor each application to ensure uniformity.

As described in further detail below, a transducer element 302 may beinstalled in a direction perpendicular to the PCB plane causing the flextabs 202 to flex (e.g., in some cases, further flex) outwardly from thePCB plane. The flexion of the flex tabs 202 may cause an elastic forceof the flex tabs 202 to be applied against opposing ends of thetransducer elements 302. The point contact 207 on the conductive pad 205of the flex tab 202 may increase the pressure applied by the flex tabs202 by reducing the contact area between the conductive ends 350 of thetransducer elements 302 and the conductive pads 205 of the flex tabs202. More particularly, when installed into the PCB 200, flexion of theflex tab pair 202A, 202B causes the first flex tab 202A to generate areactionary elastic force in the direction of the second flex tab 202Band the second flex tab 202B to generate a reactionary elastic force inthe direction of the first flex tab 202A. The elastic force may causethe first point contact 207A of the first conductive pad 205A of thefirst flex tab 202A to contact the first conductive element 350A of thetransducer element 302 and the second point contact 207B of the secondconductive pad 205B of the second flex tab 202B to contact the secondconductive element 350B of the transducer element 302. The contactbetween the first conductive pad 205A with the first conductive element350A (e.g., through the first point contact 207A) and the secondconductive pad 205B with the second conductive element 350B (e.g.,through the second point contact 207B) may create an electrical pathacross the flex tab pair 202A, 202B and the transducer element 302.

In some embodiments, with reference to FIG. 3, the PCB 200 may includeone or more alignment apertures 206 configured to aid in alignment ofthe PCB 200 during assembly of the transducer assembly and/or receiveone or more fasteners, such as screws, to mount the PCB to anothercomponent of the transducers assembly.

FIGS. 4A-4C illustrate example insertion of a transducer element 302into a PCB 200 with flex tabs 202 in accordance with some exampleembodiments of a transducer assembly 300 discussed herein. Each of thetransducer elements 302 may be a piezoelectric crystal, such as alength-poled piezoelectric crystal, configured to emit sound waves whenexcited by an electrical signal and/or emit an electrical signal whenexcited by a vibration, such as a sound wave. The transducer elements302 may include conductive elements 350 disposed on opposing ends of thetransducer elements 302, as discussed above in reference to FIGS. 2B and2C. The conductive elements 350 may be formed by any suitably highconductance material, such as gold, silver, copper, non-metallicconductors, or the like.

The transducer assembly 300 may include one or more support structures304. The support structure 304 may include an aperture 322 configured toreceive at least a portion of the transducer element 302. Additionally,the support structure 304 may also be configured to support the body ofthe PCB 200 while allowing flexion of the flex tabs 202 into theaperture 322.

The PCB 200 may be aligned and/or mounted to the support structure 304.The transducer element 302 may be press fit into the aperture 322 of thesupport structure 302 causing the flex tabs 202 to flex outwardly fromthe PCB plane 203 into the aperture 322. Flexion of the flex tabs 202cause a reactionary elastic force to be applied to the conductiveelements 350 disposed at the ends of the transducer elements 302. Withthe transducer elements 302 installed, the flex tabs 202 may beapproximately perpendicular, e.g. 90 degrees from, the body of the PCB200. In some embodiments, the mounting of the transducer element 302into the support structure 304 and/or PCB 200 may be through aninterference fit.

The flexion or bend in the flex tab 202 may prevent or limits resonatevibration translated from the transducer elements 302 to the flex tabsfrom propagating across the body of the PCB 200 as resonance waves, thusalso preventing or limiting reflected waves. The reduction orelimination of the resonance waves may be caused by a resistance, orinefficacy, of the resonate vibration to shift mode approximately 90degrees from the flex tab 202 to the body of the PCB 200. Additionally,in some embodiments, since each transducer element 302 is installedbetween a separate set of flex tabs 202, the resistance to propagationof the resonate vibration from the flex tabs 202 to the body of the PCB200 may also prevent vibrations caused by one transducer element 302from reaching a second transducer element. This reduction in the elasticresponse, e.g. resonance waves and reflected waves, may significantlyreduce undesirable signals, e.g. interference, that may otherwise effectthe sonar image.

In some embodiments, the translation of the resonate vibration, e.g.resonance waves, may be further reduced by the electrical connectionbetween the transducer elements 302 and the conductive pads 205 of thePCB 200. In this regard, since the electrical connection is made bycontact between the conductive pads 205 of the PCB 200 and theconductive elements 350 on the transducer elements 302 caused by theelastic force, solder or other fixation of the transducer elements 302to the PCB 200 is not necessary. The lack of direct mechanicalconnection, such as the solder joint 106 of the prior art, maysignificantly reduce translation of the resonate vibrations to the PCB200. Another advantage of the lack of solder joints is the removal ofvariations in mechanical boundary conditions of the electricalconnections caused by the solder joint, which may result in a sharpersonar image due to clearer and/or stronger signals to and from thetransducer elements 302.

FIG. 5 illustrates a perspective view of an example transducer assembly300 in accordance with some example embodiments discussed herein. Thetransducer assembly 300 may include a plurality of transducer elements302 inserted or mounted into the PCB 200 between flex tabs 202. Thetransducer assembly 300 may be assembled and aligned by an assemblyfixture 312, as discussed below in reference to FIGS. 11-31. FIG. 6illustrates a cross sectional view of a transducer assembly 300 inaccordance with some example embodiments discussed herein. Thetransducer assembly may include a base foam 310, a support structure 304middle foam 306, PCB 200, a top foam 308, and a plurality of transducerelements 302. The interaction of the various components of thetransducer assembly 300 are discussed below in reference to FIGS. 7-10.

FIG. 7 illustrates an exploded view of a portion of the transducerassembly 300 in accordance with some example embodiments discussedherein. The transducer assembly 300 may include a middle foam 306, e.g.a flex foam, in addition to the support structure 304 (shown in FIG. 8).The middle foam 306 may include an aperture 321 (depicted in FIG. 9) toreceive the transducer elements 302 and the flex tabs 202 of the PCB200. In some example embodiments, the middle (or other) foam may serveas the support structure supporting the body of the PCB 200 and thesupport structure 304 may not be provided.

The middle foam 306 may be any nonconductive material with a highelasticity and low creep, such as closed cell foam, rubber, or the like.The middle foam 306 may have separate apertures 321 for each transducerelement 302, to provide individual enclosures for each transducerelement 302. In some embodiments, the aperture 321 may be smaller thanor the same size as the transducer elements 302 in the longitudinaldirection of extension, such that when the flex tabs 202 flex into theaperture 321 and contact the edge of the aperture, the foam resists theflexion of the flex tabs 202. The resistance to the flexion of the flextabs 202 may cause an increase in force (e.g., a resistance force) to beapplied by the flex tabs 202 to the conductive elements 350 at the endsof the transducer elements 302.

In some embodiments, the apertures 321 may be formed by an H cut, suchthat the middle foam 306 includes a plurality of foam tabs 305configured to flex outwardly from a foam plane 307 defined by the bodyof the middle foam. The foam tabs 305 may flex with the flex tabs 202into the aperture 322 (depicted in FIG. 9) in the support structure 304and/or the base foam 310. Flexion of the foam tabs 305 may cause anelastic force to be applied to the flex tabs 202, thereby causing anincrease in the total force applied by the flex tabs 202 to the ends ofthe transducer elements 302.

FIGS. 8 and 9 illustrate exploded views of the transducer assembly 300in accordance with some example embodiments discussed herein. In someexample embodiments, the assembly fixture 312 may include one or moreguide posts 313 or ribs which may be received through one or more guideholes 315 or notches disposed in the top foam 308, middle foam 306,support structure 304, and/or the base foam 310. The one or more guideposts 313 may be further received through one or more guide holes 206 ofthe PCB 200. The guide posts 313 may be metal, plastic, or othersuitably rigid material. The guide posts 315 may project upward and awayfrom an assembly face of the assembly fixture 312. The guide post 313and guide holes 315, 206 may align the components of the transducerassembly 300 during assembly. In some embodiments, the guide holes 315,206 may also be used to mount and/or align the transducer assembly 300in a housing, such as the transducer assembly housing 400 illustrated inFIG. 10. Additionally or alternatively, the transducer assembly housing400 or other close tolerance container may be utilized to align thevarious components of the transducer assembly 300 during the assemblyprocess, such as described below in reference to FIGS. 11A-31.

The transducer assembly 300 may include a top foam 308 and a base foam310 disposed on opposing faces of the middle foam 306 (e.g., the topfoam 308 and base foam 310 may “sandwich” the middle foam 306). The topfoam 308, middle foam 306, and base foam 310 may absorb sound waveswhich are not aligned with the acoustic, e.g. emitting face, of thetransducer elements 302 of the transducer assembly 300. Additionally,the top foam 308, middle foam 306, and/or the base foam 310 may dampenradiative sound waves produced by vibration of the transducer elements302. The base foam 310 may include a plurality of apertures 324corresponding to each to the transducer elements 302 to provide anunobstructed path for emitted and received sound waves to the acousticface of the transducer assembly 300. Additionally, as discussed above,the apertures 324 in the base foam 310 may receive a portion of the flextabs 202 and/or the foam tabs 305 when they are flexed outwardly fromthe PCB plane 203 and foam plane 307 (shown in FIG. 7), respectively.

The support structure 304, e.g. crystal chassis, may be formed ofplastic, rubber, or other suitable ridged, or semi-rigid material(although, in some embodiments, the term “support structure” may referto one or more foam layers, such as may be used to replace a rigidsupport structure). The support structure 304 may include a singleaperture 322 or a plurality of apertures to receive the individualtransducer elements 302. The support structure 304 may include a singleaperture 322 in an embodiment including a middle foam 308 or othercomponent providing lateral separation of the transducer elements 302,to prevent undesirable signals, e.g. interference, caused by contactbetween vibrating piezoelectric crystals. The support structure 304 maybe disposed between the base foam 310 and the middle foam 306, and thePCB 200 may be disposed between the support structure 304 and the topfoam 308.

In some example embodiments, the support structure may include one ormore retention clips 329. The retention clips 329 may project away fromthe surface of the support structure 304. The retention clips 329 may beconfigured to receive and retain a chassis front 314 (FIG. 20B) in apredetermined position. The top foam 308, PCB 200, and middle foam 306may be “sandwiched” between the support structure 304 and the chassisfront 314, which may cause a force to be applied between the middle foam306, PCB 200, and top foam 308, thereby limiting or preventing voidstherebetween.

The top foam 308 may include an aperture 325 configured to receive anexpansion foam. The aperture 325 may extend in a longitudinal directionof extension of the top foam 308. The aperture 325 may expose thetransducer elements 302 when the transducer assembly 300 is assembled.The expansion foam may be poured through the aperture 325 around thetransducer elements and into the apertures 320 of the PCB 200, theaperture 321 of the middle foam 306, the aperture 322 of the supportstructure 304, and the aperture 324 of the base foam 310—filling voidsbetween the components. The expansion foam may harden to affix or “lock”the position of the transducer elements 302 relative to the othercomponents of the transducer assembly 300. Notably, however, theexpansion foam does not mechanically affix the transducer element to thePCB 200 or any other component of the transducer assembly 300.

FIG. 10 illustrates the transducer assembly 300 within a transducerassembly housing 400 in accordance with some example embodimentsdiscussed herein. The transducer assembly 300 may be assembled andinstalled into the transducer assembly housing 400, such as describedbelow. The transducer assembly housing 400 may provide structuralsupport and protection of the transducer assembly 300 in a marineenvironment. In some embodiments, the transducer assembly housing 400may be watertight, shock resistant, or the like. The transducer assemblyhousing 400 may be configured to house one or more transducer assemblies300 and/or one or more sensors, such as position sensors, temperaturesensors, water flow sensors, acoustic sensors, or the like.

FIGS. 11A and 11B illustrate a flow chart of a method of assembling thetransducer assembly in accordance with some example embodimentsdiscussed herein. In some embodiments, the method may includeadditional, optional operations, and/or the operations described belowmay be modified or augmented. In an example embodiment, the method mayinclude installing a release film onto the fixture assembly 312 atoperation 502. The release film may be a polyurethane sheet, or othersuitable material, which may enable the expansion foam or othermaterials to be set within the transducer assembly without adhesion tothe assembly fixture 312. Additionally, the release film may be removedrelatively easily, such as by peeling, from the transducer assembly 300(e.g., after the transducer assembly 300 is removed from the assemblyfixture 312).

The method may include cutting flex holes, e.g. apertures 324, into thebase foam 310 at operation 504 and cutting flex holes, e.g. apertures321, into the middle foam 306 at operation 506. As depicted in FIGS. 12Aand 12B, the number and arrangement of the apertures 321, 324 maycorrespond to the number and arrangement of the transducer elements 302.The apertures 321 of the middle foam 306 and/or apertures 324 of thebase foam 310 may be cut in an H pattern, e.g. H cut, thereby formingfoam tabs 305. The cuts may be executed by a dye, laser, knife, or othersuitable cutting tool.

At operation 508, the base foam 310 may be mounted to the assemblyfixture 312. As depicted in FIGS. 13A and 13B, guide holes 315 of thebase foam may be fitted onto guide posts 313 of the assembly fixture312. Additionally or alternatively, the transducer housing 400 or otherclose tolerance container may be utilized to align the variouscomponents of the transducer assembly 300 during the assembly process.

At operation 510, the crystal chassis, e.g. support structure 304, maybe mounted to the assembly fixture 312. At operation 512, the middlefoam 306 may be mounted to the assembly fixture 312. At operation 514,the flex PCB 200 may be mounted to the assembly fixture 312. Each of thesupport structure 304, middle foam 306, and PCB 200, may include guideholes 315, 206 that fit onto the guide posts 313. Additionally oralternatively, the support chassis 304 may include one or more alignmentprotrusions 311, depicted in FIG. 8, corresponding to one or morealignment recesses 309, depicted in FIG. 7. The alignment protrusions311 and alignment recesses 309 may align the middle foam 306 on thesupport structure 304 such that the apertures 321 of the middle foam 306are aligned with the aperture 322 of the support structure 304.Additionally, the alignment protrusions 311 and alignment recesses 309may restrict lateral movement of the middle foam 306 with respect to thesupport structure 304. FIG. 14A illustrates an example embodiment inwhich the middle foam and PCB 200 have been mounted on the assemblyfixture 312 and the middle foam serves as the support structure of thetransducer assembly 300. FIG. 14B depicts an embodiment including thecrystal chassis, e.g. support structure 304. The support structure 304and middle foam 306 are mounted to the assembly fixture 312. FIG. 14Cdepicts the example embodiment of FIG. 14B where the PCB 200 is alsomounted to the assembly fixture 312.

At operation 516, an expansion foam slot, e.g. aperture 325, may be cutinto the top foam 308. As depicted in FIG. 15A and 15B, the aperture 325may be elongated in the longitudinal direction of extension of the topfoam 308, such that, when assembled, the transducer elements 302 are notcovered by the top foam 308, due to being exposed via the aperture 325.The cut may be executed by a dye, laser, knife, or other suitablecutting tool.

At operation 518, the top foam 308 may be mounted to the assemblyfixture 312. As depicted in FIGS. 16A and 16B, the top foam 308 may bemounted to and/or aligned with the transducer assembly 300 by fittingguide holes 315 onto the guide posts 313.

At operation 520, flex tails 316, e.g. the off board connection portionof the PCB 200, may be inserted and aligned into a chassis front 314, asdepicted in FIG. 17. The chassis front may be metal, ridged plastic, orthe like, and be configured to restrain the middle foam 306, and topfoam 308 with the support structure 304, e.g. the crystal chassis. Atoperation 522, the chassis front 314 may be mounted to the assemblyfixture 312 via guide posts 313.

At operation 524, piezoelectric crystals (e.g., transducer elements 302)may be inserted into the flex circuit, e.g. PCB 200, by press fittingthe transducer element 302 between the flex tabs 202 of the PCB 200, asdepicted in FIG. 20A.

FIG. 19 illustrates a plurality of transducer elements 302 on anadhesive strip. In some example embodiments, the transducer elements 302may be removed from the adhesive strip, such as by tweezers and insertedinto the corresponding apertures 321 of the transducer assembly 300between the flex tabs 202, such as be a push probe, as depicted in FIG.20B.

Alternatively, two or more, such as all transducer elements 302 of thetransducer assembly 300 may be installed simultaneously. In one suchexample, a machine with a multi-head arm may be fed a plurality oftransducer elements 302, such as on the adhesive strip. The machine mayalign the plurality of transducer elements 302 with the apertures in thetransducer assembly 300. The multi-head arm may be driven toward thetransducer assembly 300, thereby pushing the plurality of transducerelements 302 into the corresponding apertures 321 between the flex tabs202 of the PCB 200. FIGS. 21A and 21B illustrate the transducer assembly300 with the transducer elements 302 installed.

At operation 526, expansion foam 381 may be provided into the expansionslot, e.g. aperture 325, such that the expansion foam 381 surrounds thetransducer elements 302 and fills the cuts, e.g. apertures, in the basefoam 310, middle foam 306, and at least a portion of the top foam 308.As depicted in FIG. 22, guard material 318 (such as paper, wax paper,polyurethane sheeting, or the like) may be installed around the aperture325 in the top foam 308. The expansion foam 381 may be poured into, e.g.across, the aperture 325 in the top foam 308, as depicted in FIG. 23.Excess expansion foam 381 may be caught by the guard material 318, whichmay be removed subsequent to completion of pouring the expansion foam381. In some embodiments, the expansion foam 381 may be poured with thetransducer assembly 300 inserted into the transducer assembly housing400, or one half of the transducer assembly housing 400 including arecess for the transducer assembly 300, such that the expansion foam 381fills gaps present between the components of the transducer assembly 300and the transducer assembly housing 400. Alternatively, a mold may beinstalled around a peripheral edge of the transducer assembly, which maybecome a portion of the transducer assembly 300, or may be removed afterexpansion of the expansion foam 381.

At operation 528, the expansion foam 381 may be allowed to expand. Fullexpansion of the expansion foam 381 may fill gaps between components ofthe transducer assembly 300 and/or lock the respective positions of thecomponents of the transducer assembly 300 relative to each other. FIG.24 depicts a “loaf” of fully expanded expansion foam 381.

At operation 530, the fixture assembly 312 may be removed from thetransducer assembly 300. FIG. 25 illustrates a transducer assembly 300with the assembly fixture 312 removed and the release sheet 323 visible

At operation 534, the release film 323 may be removed from thetransducer assembly 300, as depicted in FIG. 26. The release film 323may be peeled or otherwise removed to expose the emitting face of thetransducer elements 302.

At operation 536, the transducer assembly 300 may be installed into thetransducer assembly housing 400, if not performed previously, such as inconjunction with operation 526.

At operation 538, a flex tail positioner 327 may be installed withrespect to the transducer assembly housing 400. As depicted in FIG. 27,the flex tail positioner 327 may be installed between the flex tail 316of the PCB 200 and the transducer assembly housing 400. The flex tailpositioner 327 may cause the flex tail 316 to be directed in a directionsubstantially perpendicular to, e.g. outward and away from, the chassisfront 314 and/or transducer assembly housing 400. Other electronic wiresor cable may also be routed and secured to the transducer assemblyhousing 400, as appropriate.

At operation 540, the transducer assembly housing 400, including thetransducer assembly 300, may be placed at a predetermined tilt angle. Asdepicted in FIG. 28, the transducer assembly housing 400 may be set on atilt plate 386 set at the predetermined tilt angle, such as 5 degrees,10 degrees, 15 degrees, or the like.

At operation 542, a urethane potting material may be provided over thetransducer assembly 300. FIGS. 29 and 30 illustrate urethane 388 beingpoured into a portion of the transducer assembly housing 400, such thatthe transducer assembly 300 is completely enveloped by the pottingmaterial 388. In some embodiments, a release film may be applied to theemitting face of the transducer assembly 300 prior pouring the urethane388.

At operation 544, the urethane 388 may be allowed to cure. FIG. 31depicts the emitting face of the transducer assembly 300 in thetransducer assembly housing 400 after the potting material 388 has curedand the release film has been removed. After completion of the assemblyof the transducer assembly 300, in some embodiments, the transducerassembly housing 400 may be closed, such as by installation of a secondhalf of the transducer assembly housing 400.

Conclusion

Many modifications and other embodiments of the inventions set forthherein will come to mind to one skilled in the art to which theseinventions pertain having the benefit of the teachings presented in theforegoing descriptions and the associated drawings. Therefore, it is tobe understood that the embodiments of the invention are not to belimited to the specific embodiments disclosed and that modifications andother embodiments are intended to be included within the scope of theinvention. Moreover, although the foregoing descriptions and theassociated drawings describe example embodiments in the context ofcertain example combinations of elements and/or functions, it should beappreciated that different combinations of elements and/or functions maybe provided by alternative embodiments without departing from the scopeof the invention. In this regard, for example, different combinations ofelements and/or functions than those explicitly described above are alsocontemplated within the scope of the invention. Although specific termsare employed herein, they are used in a generic and descriptive senseonly and not for purposes of limitation.

That which is claimed:
 1. A sonar transducer assembly comprising: atleast one transducer element; a flexible printed circuit board (PCB)comprising at least one set of electrical connections for the at leastone transducer element, wherein the electrical connections comprise flextabs configured to flex out of a PCB plane defined by a body of the PCB;and a support structure comprising at least one aperture for the atleast one transducer element, wherein the support structure isconfigured to: support the body of the PCB; allow flexion of the flextabs into the aperture; and retain the at least one transducer elementin the at least one aperture, wherein the transducer element isinstalled into the aperture in a direction that is perpendicular to thePCB plane causing the flex tabs to flex outwardly from the PCB plane,wherein the flexion of the flex tabs causes an elastic force of the flextabs to be applied against opposing ends of the at least one transducerelement.
 2. The sonar transducer assembly of claim 1, wherein the atleast one transducer element is not affixed to the PCB.
 3. The sonartransducer assembly of claim 1, wherein the at least one set ofelectrical connections further comprise point contacts extendingoutwardly from the flex tabs toward the at least one transducer elementto increase pressure applied by the flex tabs on the at least onetransducer element.
 4. The sonar transducer assembly of claim 3, whereinthe point contacts each comprise a dimple in a contact pad or anelectrically conductive material added to a contact pad.
 5. The sonartransducer assembly of claim 1, wherein the at least one transducerelement comprises a plurality of transducer elements and the at leastone aperture comprises a plurality of apertures, wherein each of theplurality of transducer elements is disposed in a separate one of theplurality of apertures, wherein the support structure and PCB provideresonance isolation for each of the plurality of transducer elements. 6.The sonar transducer assembly of claim 1, wherein the support structurecomprises foam.
 7. The sonar transducer assembly of claim 6, wherein thefoam provides resistance to the flexion of the flex tabs to cause anincrease in the elastic force applied to the opposing ends of the atleast one transducer element.
 8. The sonar transducer assembly of claim6, wherein the aperture comprises an H cut configured to enable a foamtab to flex out of a foam plane defined by a foam body.
 9. The sonartransducer assembly of claim 6, wherein the support structure furthercomprises a base foam disposed on a first side of the foam and a topfoam disposed on a second side of the foam.
 10. The sonar transducerassembly of claim 9, wherein the top foam includes a slot cut configuredto receive expanding foam therethrough.
 11. The sonar transducerassembly of claim 9, wherein the base foam includes an element aperturefor the at least one transducer element, wherein the element aperture isconfigured to receive at least a portion of the flex tabs or a portionof the foam when the flex tabs are flexed.
 12. The sonar transducerassembly of claim 1, wherein the support structure comprises a chassisformed from a rigid structural material.
 13. The sonar transducerassembly of claim 1, wherein at least a portion of the transducerassembly is filled with an expanding foam that is configured to retainthe relative position of the at least one transducer element withrespect to the support structure and the PCB.
 14. The sonar transducerassembly of claim 1 further comprising: a housing configured to enclosethe at least one transducer element, the support structure, and the PCBwithin a watertight volume; and wherein at least a portion of thehousing that encloses the at least one transducer element, the supportstructure, and the PCB is filled with a potting material.
 15. The sonartransducer assembly of claim 1, wherein at least one of the PCB or thesupport structure includes a plurality of guide holes or notchesconfigured to be positioned about a guide post or rib of an assemblyfixture during assembly to align the PCB with the support structure. 16.A method of assembling a sonar transducer assembly comprising: providingat least one transducer element; mounting a flexible printed circuitboard (PCB) to a support structure, wherein the PCB comprises a set ofelectrical connections for each transducer element, wherein the set ofelectrical connections comprise flex tabs configured to flex out of aPCB plane defined by a body of the PCB, and wherein the supportstructure comprises an aperture for the at least one transducer element,wherein the support structure is configured to: support the body of thePCB; allow flexion of the flex tabs into the aperture; and retain the atleast one transducer element in the aperture; and installing at leastone transducer element into the aperture in a direction that isperpendicular to the PCB plane to cause the flex tabs to flex outwardlyfrom the PCB plane, wherein the flexion of the flex tabs causes anelastic force of the flex tabs to be applied against opposing ends ofthe at least one transducer element.
 17. The method of claim 16, whereinthe at least one transducer element is not affixed to the PCB.
 18. Themethod of claim 16, wherein the support structure comprises a foam, andwherein the method further comprises: cutting an H cut in the foam toform the aperture.
 19. The method of claim 16, wherein the at least onetransducer element comprises a plurality of transducer elements and theat least one aperture comprises a plurality of apertures, wherein eachof the plurality of transducer elements is disposed in a separate one ofthe plurality of apertures, and wherein the plurality of transducerelements are installed substantially simultaneously by a machine.
 20. Asonar transducer assembly comprising: a plurality of transducerelements; a flexible printed circuit board (PCB) comprising a pluralityof sets of electrical connections for the plurality of transducerelements, wherein each of the plurality of sets of electricalconnections comprise flex tabs configured to flex out of a PCB planedefined by a body of the PCB; and a support structure comprising aplurality of apertures, wherein each of the plurality of apertures isconfigured to receive each of the plurality of transducer elements,wherein the support structure is configured to: support the body of thePCB; allow flexion of each of the flex tabs into a respective apertureof the plurality of apertures; and retain each of the plurality oftransducer elements in the respective aperture of the plurality ofapertures, wherein each of the plurality of transducer elements is heldin the PCB and the support structure through an interference fit,wherein each of the plurality of transducer elements is installedbetween the flex tabs.
 21. The sonar transducer assembly of claim 20,wherein the plurality of transducer elements are not affixed to the PCB.22. The sonar transducer assembly of claim 20,wherein the supportstructure and PCB provide resonance isolation for each of the pluralityof transducer elements.
 23. A sonar transducer assembly comprising: atleast one transducer element; and a flexible printed circuit board (PCB)comprising at least one set of electrical connections for the at leastone transducer element, wherein the electrical connections comprise flextabs configured to flex out of a PCB plane defined by a body of the PCB;wherein the at least one transducer element is installed between theflex tabs, wherein flexion of the flex tabs causes an elastic force ofthe flex tabs to be applied against opposing ends of the at least onetransducer element.
 24. The sonar transducer assembly of claim 23,wherein the at least one transducer element is not affixed to the PCB.25. The sonar transducer assembly of claim 23, wherein the at least oneset of electrical connections further comprise point contacts extendingoutwardly from the flex tabs toward the at least one transducer elementto increase pressure applied by the flex tabs on the at least onetransducer element.